Generally, a thermo-magnetism cycle apparatus is used as a heat pump or heat engine. Patent documents 1 to 4 (i.e., Patent document 1: Japanese Patent Laid-Open No. 2012-255642; Patent document 2: Japanese Patent Laid-Open No. 2012-229634; Patent document 3: Japanese Patent Laid-Open No. 2012-503754; Patent document 4: Japanese Patent Laid-Open No. 2012-518149) respectively disclose a thermo-magnetism cycle apparatus using temperature characteristics of a magnetic body. As a heat pump, the apparatus provides either a low temperature or removes heat via a changing of a magnetic field. As a heat engine, the apparatus removes thermal energy via the changing of the magnetic field caused by a temperature difference.
Further, the patent document 4 provides an apparatus which transfers heat by using respectively different heat transfer media in a high temperature region and a low temperature region. In the proposed apparatus, a heat exchange device is used to exchange heat between the two media. The heat exchange device is a heat conductive member arranged between the two media. With such a configuration, heat in the proposed apparatus is transferred through a heat conductive member having a rod shape.
The heat conductive member disclosed in the patent document 4 transfers heat only by heat conduction. Such a configuration results in undesired heat loss in the thermo-magnetism cycle apparatus. That is, the heat conductive member must have a partial reverse temperature gradient provided therein, which is a reverse gradient relative to the main temperature gradient between a low temperature end and a high temperature end.
For example, as shown in FIG. 1, a heat pump apparatus provided with a first unit 11a on a low temperature side and a second unit 11b on a high temperature side is considered. When heat transfer between the two units is provided only by the heat conductive member, a temperature distribution may look like a broken line CMP, together with temperature T1 and T2c on both ends of the heat conductive member. Due to the heat conduction therebetween, a relationship of temperature T1 and temperature T2c is T1>T2c. However, a partial temperature gradient of T1>T2c is a reverse gradient relative to a main temperature gradient of TC<THc, which is a gradient between TC (i.e., a low-temp end temperature) and THc (i.e., a high-temp end temperature). As a result, such a thermo-magnetism cycle apparatus has a deteriorated efficiency.
From another viewpoint, a long rod-shaped heat conductive member in the patent document 4 is not capable of providing efficient heat exchange between two media. Therefore, the efficiency as a thermo-magnetism cycle apparatus decreases. For example, the difference of temperature made in the heat pump is small. Also, the power obtained from the engine is small.
From the above-mentioned viewpoint and/or from the other viewpoints, thermo-magnetism cycle apparatus is required to have a further improvement.